Due to the characteristics of nacelle acoustic liners, such as variable curvature, numerous holes, and tiny hole diameter and spacing, traditional drilling techniques are difficult to meet the needs of acoustic liner drilling. To improve the drilling efficiency and quality of the nacelle acoustic liner of a large aircraft’s aero-engine, a robotic drilling system with multi-spindle capabilities was developed. A multi-spindle drilling end-effector capable of machining acoustic array holes is designed to address the needs of drilling nacelle acoustic liner components. The end-effector can drill multiple small holes with a single positioning. Considering the complex curved shape of the acoustic liner and the robot’s reachability, a rotatable fixture table was designed to adjust the machining pose of the acoustic liner. An evaluation index for robot machining state was constructed by integrating multiple factors such as singularity, joint limits, and robot stiffness. A zoning scheme of the nacelle acoustic liner for machining was studied based on the layout characteristics regarding the robot and workpiece of the multi-spindle drilling system. The processing parameters for holes of composite acoustic liner are determined by drilling process tests. The results show that the drilling efficiency of multi-spindle drilling system is 4.37 times that of single-spindle systems. The zoning for machining ensures optimal processing conditions for each drilling point. Using a spindle speed of 30000 r/min and a feed rate of 700 mm/min, defects often occurring in drilling, such as burrs and splits, are effectively avoided, reducing the delamination factor to 1.267, which can meet the manufacturing
requirements of aero-engine nacelle acoustic liners and also has significance as a reference for high-density array hole processing in other fields.